A University of Alaska Fairbanks-led research team has developed a way to use satellite images to determine the amount of methane being released from northern lakes, a technique that could help climate change modelers better account for this potent greenhouse gas.

By using synthetic aperture radar, or SAR, researchers were able to find a correlation between "brighter" satellite images of frozen lakes and the amount of methane they produce. Comparing those SAR images with ground-level methane measurements confirmed that the satellite readings were consistent with on-site data.

SAR data, which were provided by UAF's Alaska Satellite Facility, are well-suited to the Arctic. The technology can penetrate dry snow, and doesn't require daylight or cloud-free conditions. SAR is also good at imaging frozen lakes, particularly ones filled with bubbles that often form in ice when methane is present.

"We found that backscatter is brighter when there are more bubbles trapped in the lake ice," said Melanie Engram, the lead author of the study and a researcher at UAF's Water and Environmental Research Center. "Bubbles form an insulated blanket, so ice beneath them grows more slowly, causing a warped surface which reflects the radar signal back to the satellite."

The new technique could have significant implications for climate change predictions. Methane is about 30 times more powerful than carbon dioxide as a heat-trapping gas, so accurate estimates about its prevalence are particularly important in scientific models.

Previous research had confirmed that vast amounts of methane are being released from thermokarst lakes as the permafrost beneath them thaws. But collecting on-site data from those lakes is often expensive and logistically challenging. Because of that, information about methane production is available from only a tiny percentage of Arctic lakes.

"This new technique is a major breakthrough for understanding the Arctic methane budget," said UAF researcher Katey Walter Anthony, who also contributed to the study.

"It helps to resolve a longstanding discrepancy between estimates of Arctic methane emissions from atmospheric measurements and data upscaled from a small number of individual lakes."

To confirm the SAR data, researchers compared satellite images with field measurements from 48 lakes in five geographic areas in Alaska. By extrapolating those results, researchers can now estimate the methane production of more than 5,000 Alaska lakes.

"It's important to know how much methane comes out of these lakes and whether the level is increasing," Engram said. "We can't get out to every single lake and do field work, but we can extrapolate field measurements using SAR remote sensing to get these regional estimates."

Related Links
University Of Alaska Fairbanks
Beyond the Ice Age

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

US Navy ships in Barents Sea near Russia, 1st time since 1980s
Washington (AFP) May 4, 2020
The US Navy sent four ships this week to conduct Arctic security operations in the Barents Sea north of Russia for the first time in over three decades, the Pentagon said Monday. The move came as US officials said rivals like China and Russia were increasingly testing US defense resolve with their own air and sea challenges during the coronavirus pandemic. The four vessels, along with a British Royal navy ship, conducted operations in the increasingly strategic Arctic region "to assert freedom o ... read more